These constraints are considerably smaller than the limit of \(\lesssim 3 \times 10^{-15}\)  placed with GW170817 [1]}. This can be understood by remembering that this limit was based off of a time delay of \(\sim 5\)  seconds.
However, a shift of even milliseconds in a gravitational-wave signal can be observable with matched-filtering and so we are able to probe
much smaller values of \(\delta c_{\rm GW}\) .
